1. Field of the Invention
This invention relates to a method of processing a cheese processing waste stream.
2. Discussion of the Background
Whey is a major by-product of cheese making, which, for environmental reasons, presents a difficult waste disposal problem. Whey is typically composed of about 5 wt. % lactose, 1 wt. % protein and about 0.5 wt. % salts, where the balance of the mixture is water. While the protein component can often be recovered by ultra-filtration, and accordingly used in food products, the lactose component has heretofore been of little value.
Even though major cheese making countries continue to explore methods for disposing and utilizing fluid whey, the magnitude of the waste disposal problem requires that improved disposal methods be developed. In 1993 it was estimated by the Dairy Products Annual, USDA that over 62.6 billion pounds of fluid whey were produced in the United States alone. Conventional disposal methods for fluid whey include use as fertilizer, use as a liquid animal feed, use in food products, drying and dumping.
Thomas U.S. Pat. No. 4,001,198 reports a method of recovering nutrients from cheese whey by multiple ultrafiltration steps, in which proteins, lactose and small molecular weight molecules are successively removed. The remaining permeate is then oxygenated to lower the biological oxygen and chemical oxygen demands, so that the permeate can be dumped safely.
Chambers et al. U.S. Pat. No. 4,547,386 report the preparation of animal feed blocks from whey, in which whey is concentrated to a solids content of at least 45%, followed, by addition of a divalent cation, to promote gelling of the structure.
Melnychyn U.S. Pat. No. 4,968,521, reports the use of fluid milk by-products as an extraction solvent for raw vegetable material in the production of a new human food or animal feed.
Armstrong U.S. Pat. No. 4,617,861 reports the processing of cheese whey by separation of the whey proteins, followed by fermentation of lactose to produce ethanol and fermentation solubles. The protein fraction is used as a food source, the ethanol as an industrial fuel and the fermentation solubles as an animal feed supplement.
Pederson, Jr. U.S. Pat. No. 4,202,909 reports using ultrafiltration to reduce the mineral content of cheese whey, thereby making it easier to obtain relatively high purity lactose.
Harju et al. U.S. Pat. Nos. 4,971,701 and 4,855,056 report the demineralization of cheese whey by means of a four-compartment electrolytic cell.
Harmon et al. U.S. Pat. No. 4,543,261 report the separation of soluble salts from non-ionic low molecular weight organic compounds, by passing an aqueous liquid through a bed of a gel-type strongly acidic cation exchange resin.
Shimatani et al. U.S. Pat. No. 5,118,516 report the isolation of sialic acid-containing lactose, from whey, skim milk or a deproteinized solution by (a) electrodialysis, or (b) ion exchange by a cation-exchange resin and a strongly basic anion-exchange resin, or (c) a combination of electrodialysis and ion exchange by the cation-exchange resin and the strongly basic anion-exchange resin to desalt the permeate.
Shimatani et al. U.S. Pat. No. 5,270,462 report a process of manufacturing a composition containing a high concentration of sialic acids, by adjusting the pH of cheese whey to be acidic, contacting the whey with a cation exchanger, followed by concentrating and desalting the eluent.
JP Kokai 01-168,693 reports the preparation of a sialic acid composition, by subjecting milk, non-fat milk, buttermilk or whey to ultrafiltration, fractionating at 20,000 to 500,000 Daltons at a pH of 4.0 to 6.0, followed by a second ultrafiltration, fractionating at 1,000 to 10,000 Daltons at a pH of 6.0 to 8.0 under 0.2 to 2.0 MPa, to remove impurities such as lactose. The residual is spray dried or lyophilized.
JP Kokai 03-143,351 reports the recovery of oligosaccharide bonding type sialic acid from an alkali cleaning waste liquid of anion exchange resin formed at desalting of whey, by neutralization, ultrafiltration, reverse osmosis, desalting, absorption of the sialic acid onto a strong basic type anion exchange resin, followed by elution, desalting and drying.
JP Kokai 59-184,197 reports the manufacture of oligosaccharides attached to sialic acids, by desalting a sialyloligosaccharide-containing molasses, passing the desalted solution through an anion exchange column, neutralizing the eluate and desalting the eluate by electrophoresis.
Accordingly, processing cheese processing waste streams by extraction of valuable components by ion-exchange chromatography have been reported. The ion-exchange based methods for removing sialyloligosaccharides from a cheese processing waste stream, suffer from the difficulty in isolating the sialyloligosaccharide from the ion-exchange column. Specifically, the absorbed sialyloligosaccharide is eluted by treatment of the column with several column volumes of an aqueous salt solution such as NaCl and NaOAc. The result is an eluent of a very dilute solution of the sialyloligosaccharide and a high concentration of salt. In order to separate the sialyloligosaccharide from the eluent, the eluent is subjected to desalting techniques such as reverse osmosis, which separates the sialyloligosaccharide from the salt. However, reverse osmosis is a slow technique and very energy intensive. Accordingly, any isolation procedure, which could avoid a desalting step by reverse osmosis would be advantageous.
Despite many creative methods of disposing of waste fluid whey, the ever increasing supply of cheese whey demands more effective waste disposal methods.
The present invention addresses this problem by providing a method of processing a cheese processing waste stream, which provides for the economic disposal of the material.